This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
An ad hoc mode of operation of WLAN networks is a potential mechanism by which a WLAN network's coverage area can be extended. The ad hoc mode in the 802.11 standard allows a device's radio network interface card (NIC) to operate in what is referred to as an independent basic service set (IBSS) network configuration. With an IBSS, there are no access points. Instead, individual user devices communicate directly with each other in a peer-to-peer manner. There are currently ongoing efforts to define MESH networks, with an intent of configuring a few nodes in the network to operate in an ad hoc mode of operation.
In an ad hoc mode of operation, a requesting station needs to be awake during an ATIM window period which follows a transmitted beacon in order to be informed if any other station in the WLAN network has any data queued for it or if the requesting station has data for another station. If either there is data queued to send to another station, and the other station is awake, or if any other station has data queued for the station at issue, then the requesting station is expected to remain on until the next beacon interval. However, the amount of data destined for respective stations within a WLAN network can be very limited, the data may be periodic, and data frames may belong to different traffic classes. As such, there is a need to limit the amount of signaling that is required to ensure that a WLAN station or piece of equipment is awake to receive the data that is queued for it.
FIG. 1 shows how a plurality of stations operating in an ad hoc mode currently operate. During an ATIM period, a requesting station STA0 transmits a separate poll packet 100 to each of a plurality of receiving stations (STA1 to STAn in FIG. 1) to determine if the respective receiving station is awake. If a receiving station is awake, then the respective receiving station transmits an acknowledgment message 110 to the requesting station STA0. The requesting station STA0 then assumes that the receiving station will remain awake until the next ATIM period. The requesting station STA0 that transmits the poll packets 100 maintains a list of receiving stations that transmitted an acknowledgment message 110 to the requesting station STA0. This process occurs for each station within the ad hoc network, as receiving stations become requesting stations and vice versa.
Under this system depicted in FIG. 1, the requesting station STA0 knows whether it can transmit data after the ATIM period or not if there is at least one acknowledgment from any other station (i.e., at least one receiving station responds with an acknowledgment message 110). Also, the requesting station STA0 knows if there is any other station in the system that has data for the requesting station (i.e., any station that has sent the station at issue a poll message 100). However, if even a single receiving station responds with an acknowledgment message 110, then the requesting station STA0 will have to remain awake for the entire ATIM period, as the receiving station, for example STA1, does not know how much data it will receive from the requesting station STA0.
It is therefore desirable to provide a system by which a receiving station STA0 does not have to remain awake until the next ATIM period unless it is necessary to do so.